Suspension clamps for overhead electric conductors



May 11, 1965 GIBBON SUSPENSION CLAMPS FOR OVERHEAD ELECTRIC CONDUCTORS Filed June 25, 1963 3 Sheets-Sheet l ll 8 2 H j I 1 n 7 In ventor Attorney May 11, 1965 W. GIBBON SUSPENSION CLAMPS FOR OVERHEAD ELECTRIC CONDUCTORS Filed June 25,' 1963 3 Sheets-$heet 2 ORS May 11, 1965 W- GIBBON SUSPENSION CLAMPS FOR OVERHEAD ELECTRIC CONDUCT 3 Sheets-Sheet 5 Filed June 25, 1963 I I ventor By I @AM M L Attorney United States Patent 3,182,933 SUSPENSION CLAMPS FOR OVERHEAD ELECTRIC CONDUCTORS William Gibbon, Childwall, Liverpool, England, assignor to British Insulated Callenders Cables Limited, London, England, a British company Filed June 25, 1963, Ser. No. 290,442 Claims priority, application Great Britain, July 5, 1962, 25,816/ 62 6 Claims. (Cl. 248-63) This invention relates to suspension clamps for overhead electric conductors. Such clamps in general use usually comprise a trough-shaped clamp body for the reception of an overhead conductor and means for retaining such conductor in the clamp body. The clamp body is generally suspended from an insulator or insulator string by a stirrup of inverted EJ-shape or a two-part strap, each limb of which is provided with .a hole or slot which engages one of a pair of trunnions projecting laterally from opposite sides of the body so that the body is free to pivot on the trunnions. Suspension clamps of this kind will hereinafter be referred to as of the kind described.

In the past suspension clamps of the kind described have generally been made of malleable cast iron but in order to reduce the weight of the clamps and in order to avoid the power losses due to hysteresis and eddy currents in the ferrous material of the clamps, the clamps have more recently been manufactured of a lightweight non-ferrous metal or non-ferrous metal alloy, e.g. an aluminium alloy. It has been found, however, that the trunnions of a clamp made of such a lightweight metal or metal alloy are liable under operational conditions to become badly worn when the clamp is subjected to continuous oscillatory movement due to the effect of wind and changes in tension of the overhead conductor.

It is an object of the present invention to provide, for a suspension clamp of the kind described, an improved form of trough-shaped clamp body of non-ferrous metal. The term non-ferrous metal as used in the specification and in the claims which form part thereof is used broadly to include non-ferrous metal in a substantially pure form or alloys.

In accordance with the invention the trough-shaped clamp body has projecting laterally from its opposite sides trunnions each comprising a core integral with the body and tightly embracing the core a bushing of wear-resisting metal so fitted on the core that rotation of the bushing relative to the core is prevented, the external peripheral surface of the bushing being asymmetrical about a horizontal plane containing the core axis and the part of the bushing lying below said plane comprising an externally rounded base portion whose wall thickness is substantially greater than that of the remainder of the bushing.

Relative rotation between the bushing and the core, which might result in the thinnest part of the wall of the bushing moving down to the underside of the trunnion, is preferably prevented by making at least a part of the length of the core and of the bore of the bushing into which the core fits of non-circular shape, for example of square cross-section. Alternatively relative rotation between the bushing and the core may be prevented by the provision of an auxiliary locking device, for example a locking member which engages the two parts. This member may take the form of a pin which passes through the wall of the bushing into the core, or it may comprise at least one projection integral with or carried by one of the two parts forming the trunnion which engages in a keyway provided in the other of the two parts.

In cases where the method used to prevent rotation of the bushing on the core does not also result in the prevention of axial displacement of the bushing on the core, such displacement may be prevented by axially compressing the 3,182,938 Patented May 11, 1965 core towards the clamp body to an extent to cause all or a part of the free end of the core to be forced radially outward and against the end face of the bushing. Axial compression of the core may also be to an extent to cause the peripheral surfaces of the core to be forced radially outward against the internal surface of the wall of the bushing and so assist in preventing relative rotation between the bushing and the core.

The free end of each bushing may be provided with an outwardly projecting flange which extends over all or a part of the periphery of the bushing positively to prevent lateral displacement of the limb of the support stirrup or strap under operational conditions. Preferably the flange is in the form of a lip which is dependent from the periphery of the base portion of the bushing.

The clamp is preferably a casting of an aluminium alloy, e.g. an alloy consisting mainly of aluminium, silicon and magnesium, and in this case the bushings are preferably of galvanised cast iron. Alternatively the bushings may be of steel, for instance stainless steel.

The invention will now be described in more detail, and by way of example, with reference to the accompanying drawings, in which:

FIGURES l and 2 are side and end elevations respectively of our preferred form of suspension clamp,

FIGURE 3 is a section taken on the line III-III in FIGURE 1 with the cover plate and Ubo1ts omitted,

FIGURE 4 is a sectional view of a trunnion of the clamp taken on the line IVIV in FIGURE 3 with the limb of the two-part strap omitted,

FIGURE 5 is an end view of an alternative form of trunnion with the clamp body and the two-part strap omitted,

FIGURES 6 and 7 are sections taken on the line VIVI in FIGURE 5 and on the line VIIVII in FIG- URE 6 respectively,

FIGURE 8 is an end view of a third form of trunnion with the clamp body and the two-part strap omitted,

FIGURES 9 and 10 are sections taken on the line IX-IX in FIGURE 8 and on the line XX in FIGURE 9 respectively.

FIGURE 11 is an end view of a fourth form of trunnion with the clamp body and the two-part strap omitted and FIGURES 12 and 13 are sections taken on the line XIIXII in FIGURE 11 and on the line XIII-XIII in FIGURE 12 respectively.

The suspension clamp shown in FIGURES 1 to- 4 comprises a trough-shaped clamp body 1 of an aluminium alloy consisting mainly of aluminium, silicon and magnesium in which an overhead conductor can be clamped by a cover plate 2 and a pair of U-bolts 3. The clamp body 1 can be suspended from an insulator or insulator string (not shown) by a two-part strap 4 of galvanised mild steel. Each limb 5 of the strap 4 has a slot 6 which engages one of a pair of trunnions 7 projecting laterally from opposite sides of the clamp body 1 sothat the body is free to pivot on the trunnions.

Each trunnion 7 comprises a core 8 integral with the body 1 and a bushing 9 of malleable cast iron that tightly embraces the core. The core 8 and the bore of the bushing 9 are of circular cross-section over the greater part of their length but, in order to prevent rotation of the bushing on the core, a short portion 10 of the core at its free end and the corresponding portion of the bore of the bushing are of square cross-section. To prevent axial movement of the bushing 9 on the core 8 the core is compressed axially towards the body 1 to force the free end of the core radially outward and against the end face of the bushing to form an overlying lip 14. The bore of the bushing 9 is so located in the bushing that the externally rounded base portion 12 of the bushing, lying below a horizontal plane containing the core axis has a wall thickness that is substantially greater than that of the re mainder of the bushing. At the free end of the bushing 9, the base portion 12 has a lip 13 to prevent lateral displacement of the limb of the strap 4.

Each of the three alternative forms of trunnion illustrated in FIGURES 5 to 13 comprises a core integral with a trough-shaped clamp body of non-ferrous metal and a bushing of wear-resisting metal and in each of these examples the bushing is so fitted on the core that an externally rounded base portion of the bushing having a Wall thickness that is substantially greater than that of the remainder of the bushing. In each case, however, rotation of the bushing on the core is prevented by fitting the bushing on the core in a different manner.

' In the trunnion shown in FIGURES 5 to 7, the core 18 and the bore of the bushing 19 are of square crosssection over the whole of their length to prevent relative rotation between the two parts. Axial displacement of the bushing 19 is prevented as before by axial compression of the core 18 towards the body to force the free end of the core radially outward and against the end face of the bushing. FIGURES 8 to show a trun nion in which a bushing 39 tightly embraces a core 38 ;of circular cross-section and in which relative rotation between'the two parts is prevented by a steel pin 37 which passes throughthe upper half of the wall of the bushing into the core. In the trunnion illustrated in FIGURES 11 to 13, a core 48 is provided with three ribs 47'which extend along the whole length of the core and these engage in three kcyways provided in the bore of a bushing 49 fitted on the core. Axial displacement of the bushing 49 on the cor-e 48 is prevented as previously described by axial compression of the core.

In each of the trunnions described a lip dependent from the base portion at the free end of the bushing serves to prevent lateral displacement of a limb of the two-part strap.

I claim:

1. For a suspension clamp for an overhead electric conductor comprising a trough-shaped clamp body for reception of the conductor and means for suspending said body from a support, a trough-shaped body comprising:

(a) a part of a non-ferrous metal for reception of the conductor, and

(b) trunnions projecting laterally from opposite sides of said part for engaging said suspending means, each of said trunnions comprising:

(i) a core integral with and of the same nonferrous metal as said part, and (ii) a bushing of Wear-resisting metal having a base portion which has a wall thickness substantially greater than that of the remainder of the bushing and which is formed with an externally rounded periphery, said bushing tightly embracing the core in such a way that the base portion of the bushing lies below a horizontal plane containing the core axis, and (iii) means for preventing rotation of the bushing relative to its core.

2. A clamp body as claimed in claim 1, wherein the bushing of each trunnion has, at its free end, an outwardly projecting flange extending over at least a part of the periphery of the bushing positively to prevent lateral displacement of said suspending means.

3. A clamp body as claimed in claim 2, wherein the flange is in the form of a lip which is dependent from the periphery of the base portion of the bushing.

4. For a suspension clamp for an overhead electric conductor comprising a trough-shaped clamp body for reception of the conductor and means for suspending said body from a support, a trough-shaped body comprising:

(a) a part of non-ferrous metal for reception of the conductor, and

(b) trunnions projecting laterally from opposite sides of said part for engaging said suspending means, each of said trunnions comprising:

(i) a core integral with and of the same nonferrous metal as said part, and

(ii) a bushing of wear-resisting metal having a base portion which has a wall thickness substantially greater than that of the remainder of the bushing and which is formed with an externally rounded periphery, said bushing tightly embracing the core in such a way that the base portion of the bushing lies below a horizontal plane containing the core axis, and

(iii) a locking device for preventing rotation of the bushing relative to its core.

5. For a suspension clamp for an overhead electric conductor comprising a trough-shaped clamp body for reception of the conductor and means for suspending said body from a support, a trough-shaped body comprising:

(a) a partof non-ferrous metal for reception of the conductor, and

(b) trunnions projecting laterally from opposite sides of said part for engaging said suspending means, each of said trunnions comprising:

(i) a core integral with and of the same nonferrous metal as said part and of non-circular cross-section over at least a part of its length, and

(ii) a bushing of wear-resisting metal having a bore of corresponding shape to that or" the core and having a base portion which has a wall thickness substantially greater than that of the remainder of the bushing and which is formed with an externally rounded periphery, said bushing tightly embracing the core in such a way that the base portion of the bushing lies below a horizontal plane containing the core axis.

6. A clamp body as claimed in claim 5, wherein each core is axially compressed towards said part to cause at least a part of the free end of the core to be forced radially outward and against the end face of its bushing where,- by axial displacement of the bushing on the core is positively prevented.

References Cited by the Examiner UNITED STATES PATENTS 109,681 11/70 Smith 28753 536,048 3/95 Schofield 308237 634,256 10/99 Atherton 287-63 1,254,726 1/18 Portee 287-53 1,370,073 3/21 Utz et al 287-53 1,803,995 5/31 Chilton 28753 1,966,258 7/34 McCoy 248-63 1,973,556 9/34 Bolser 248-63 2,039,501 5/ 36 Taylor 248-63 2,058,258 10/36 Prieswerk 24863.

, FOREIGN PATENTS 504,456 4/39 Great Britain.

803,147 10/58 Great Britain,

313,739 1/34 Italy.

CLAUDE A. LE ROY, Primary Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,182,938 May 11, 1965 William Gibbon It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 13, after "bushing" insert lies below a horizontal plane containing the core axis Signed and sealed this 21st day of September 1965.

SEAL) Ltlest:

ERNEST W. SWIDER EDWARD J BRENNER Ittesting ()fficer Commissioner of Patents 

1. FOR A SUSPENSION CLAMP FOR AN OVERHEAD ELECTRIC CONDUCTOR COMPRISING A TROUGH-SHAPED CLAMP BODY FOR RECEPTION OF THE CONDUCTOR AND MEANS FOR SUSPENDING SAID BODY FROM A SUPPORT, A TROUGH-SHAPED BODY COMPRISING: (A) A PART OF A NON-FERROUS METAL FOR RECEPTION OF THE CONDUCTOR, AND (B) TRUNNIONS PROJECTING LATERALLY FROM OPPOSITE SIDES OF SAID PART FOR ENGAGING SAID SUSPENDING MEANS, EACH OF SAID TRUNNIONS COMPRISING: (I) A CORE INTEGRAL WITH AND OF THE SAME NONFERROUS METAL AS SAID PART, AND (II) A BUSHING OF WEAR-RESISTING METAL HAVING A BASE PORTION WHICH HAS A WALL THICKNESS SUBSTANTIALLY GREATER THAN THAT OF THE REMAINDER OF THE BUSHING AND WHICH IS FORMED WITH AN EXTERNALLY ROUNDED PERIPHERY, SAID BUSHING TIGHTLY EMBRACING THE CORE IN SUCH A WAY THAT THE BASE PORTION OF THE BUSHING LIES BELOW A HORIZONTAL PLANE CONTAINING THE CORE AXIS, AND (III) MEANS FOR PREVENTING ROTATION OF THE BUSHING RELATIVE TO ITS CORE. 